District



' A E. E. CLEMENT IO BROADCAST SELECTING AND DISTRIBUTING SYSTE"Original Filed Feb. 29, 1924 saw/1 70 Jun 'i matter;

' thus'supplied from central 1166 ei sue! Dec. 11, 1928.

NITEDSTATE A ENT O FICE- r nnwaan E. animus,

ori inai No. 1,522,360, d ted January 6,

1 reissue flied January My inventionrel'ates to systems for radio"broadcast distribution and hasfor its object o to renderit possible forvery simple type of receiving apparatusito Jbe able to select with:certainty and'receive within the range of the present high powered longrange receivers, such asthe ,supere l'h y e- It is an object of myinventiontoprovide additiomrl receiving apparatus at the central stationadapted to tion for the detection of the signal-modulaline circuitsatype of current which willprove suitable for communication back andforth 'Otherobjects will suificiently appear herein- Y I- attain my byproviding each suhscriber tothe system with a receiving 'antennaandvtuned secondary circuit as usual, and I supply each subscriber froma central stathec'arrier current'receivedfrom anypar- 'ticular ordesired distant station, 'Inorder to; beable to do this, linstall at acentral station a plurality of oscillators tunedto differentfrequencies, and I'provide theoutor the like, so that nected with thesubscribcrs wired lines. In the connectingcircuits, whichmay be ordi--nary cord circuits w cillator currents,- and since their plate circuitsare connected to the, lines theyisup ply the latter withunmodulatedpulsating igh. 1 frequency.

' scribersstation in ,one sideof-either' 9. (iiig-Inone form oftheinvention, th currents the received modulated radio waves to prov I-1duce locally an amplified modulated asym- 1925, Serial no; 695,993,filed February 29,1924. 5, 1-927. Serial mymmsv subscribers with a iwith ample power from any distant station.

cooperate with the simple receiving apparatus at the subscriber s stak'tions and at the same time to supply to'the being received in a anordinary radio telephone receiver, when ''between the subscribersand theoperator..

' tion with 1. unmodulated pulsating current at a frequency suitable toheterodynewith' panying rawing i Wh "central connecting c1rcuits for thesame, together with oscillators at the central station; Y Figs. 2 and 3show special put terminals'of theseoscillator-circuits with Y scribersreceivers; "proper switching terminals, such as jacks" they can beintercon- 'centr'alstation and S I ith terminal plugs, pro 1 vided] atthe central oflice for connecting oscilla'torsto-t esubscribers lines, Ipro- Q vide detector tubes, which rectify the ,os-

as plug cordncircuits' A an a A has a plug P and a plugPf. connected: byheterodyningfi currents, These currents are taken in at"thefrsubferential circuit or? ina 'difierential receiver ,andthereincombined-with the. modulated. I radio currentsre'ceived over the antennafcirbined with Senorita-may take R nate name nnoancasr snnnc'rmo' ANDnrs'rnmurme sYs'rnu.

Application 101' imetricbeat wave, which is, capable of being receivedon anrordinary radio telephone ,re- CGIYBI'. However, various types oflocal or wasarnemon, manner or commnm, Assmiwoa 'ro EDWARD r. COLLADAY',or wasrmmron, ms'mrc'rqorconumnmu heterodyning circuitsor instrumentsmay he employed, the invention residing particularly in the supply andtransmissionffrom the central station of unmodulated oscillator currentat diflerent frequencies, toenable the subsomber to make selection byheterodyning without thetrouble of elaborate apparatus or tuning at hissubstation. An ancillary but yeryl important feature of the'inventionisthe furnishing of unmodulated pulsating current for heterodyningwhereby the beat 7 wave will be an asymmetric modulatedwave, capable ofsimple receiver set or in properly connected, w thout further detection,thus obviating the 'rality of detectors atthe subscribers stations.

Furthermore, the type ofcurrentthus supn plied inthe line,circuitsissuitable for communication back and forth between scribers and theoperators.

o invention is illustrated the subforms of sub- Referring to thedrawing, Fig. C is a is a. subscriberssta:

necessity fora plution. At the former I locate oscillators ,O, n

O, f etc;, having their circuits ,connecte tozs'witching terminals J, JJF, etc, whereby they, may be interconnected with the switchingterminals J ofsubscribers lines. The switching terminalsin thedrawingsare shown as jacks, and the connecting means 7 d B, The cord s dt r 2,

the input, or gridcircuit of atubesdetectqr D, the plate or outputcircuit of which s B to line wires 5 -6-leading to the. subscribersstation.

connected through the plug 3, 4, 1 and3-constitutijng Sh w in, Fee 2 an-1 R se s 2 r m a tion C sents a type ofFessenden receiver, in which onecoil is connected to line, and the other is coupled to the receivingantenna, one of the coils being preferably associated in fixed relationwith the diaphragm in the well known manner. In Figure 3 is shown anequivalent; arrangement of coils in which the received waves and thosesupplied from central are both supplied in the plate circuit of thedetector tube extended, instead of being confined in separate circuitsas in the Fessenden type receiver shown in Fig. 2. It is a parent that,in either case, with proper ection of oscillator frequency at thecentral station, the signal is made audible in the subscribers radioreceiver without the need scri ers station. I

It is to be understood that it is within the spirit of my inventionto'make the receiving apparatus 8 at the subscribers station of anydesired type, there being no need to limit it to the simple types ofreceiving apparatus herein mentions It is, portant feature of myinvention that the results attainable with a simple receiver apparatusconnected according to my invention, are on a par with those usuallyattainable on] with a high powered long range receiver suc as thesuperheterodyne' i e service rendered by the central stato itssubscribers includes a certain range in point of distance, and also acertain range. in point of wave lengths through which select-ions can'be made under, the supervision of the operators. For example, from 200130600 meters is the usual range of short wave lengths used in ordinartelephone broadcasting. The wave lengt s an plied by the oscillators O,O, 0 should e Such. that they will form a heterodyning scalewith thebroadcasting wave lengths of the stations. listed and intended to bereceived bythe subscriber. Each subscriber will have to do his owntuning aszat present,

so hr'ashisantenna circuit'and local receiv'i'ng circu t is concerned,but this is when the instrument is calibrated simple and standardized,involving merely the setting of'the variable condensers or equivalentpapparatus to readings taken from a table. eydnd; thislthe subscriberhas nothing to do except to ask central for the station wanted. He isthereupon supplied with unmodulated oscillator current of such afrequency that the difference between it and the frequency .of the wavesused by the station wanted, will be theuniform beat frequency to whichall thed subscribers instruments 7 are standardihe' a I 'The 0 erator isprovided in each cord circuit with a key K by means of which she caninclude her headset Hfin the plate circuit and therefore in series withthe line and the subscribers instrument. It is possible for Iproviding aseparate'detector at the subwired line however, an imfrequency to makethis a bridging arrangement by,

using a bridging battery in the plate circuit, with radio and audiochoke coils in the battery bridge. The, plate-filament branch of thetube, the subscribers circuit, and any temporary connection of theoperators set would then all be in parallel with the battery, and thesubscriber and the operator can talk back and forth over the circuit ofthe high frequency high potential pulsatingplate current. The same istrue of the series arrangement.

I claim: p

1. In a system of radio broadcast distribution, a central station andsubscribers stations and wired linecircuits interconnecting them, meansat a subscribers station for receiving modulated radio frequency carrierwaves, means at the central station for supplying the subscribersstation over said with unmodulated periodic current atsuch' a frequencyas will heterodyne with the modulated waves received at the subscribersstation, to produce a standard modulated beat wave in the subscribersreceiver.'

2. In a system of radio broadcast distri-' bution, a central station andsubscribers? stations and wired line circuits interconnecting them,means at the subscribers station for receiving ether'waves, means at thecentral station for generating unmodulated periodic current, switchingmeans for connecting said central office generators interchangeably withsaid subscribers wired line circuits, and audio receivers at thesubscribers station responsive to modulations carried on thestandardbeat waves due to the composition of the modulated and the unmodulatedwaves received through the ether and through the line circuitsrespecstations and wired line circuits interconnecting them, anoscillator circuit at the central office,

switching terminals therefor, switching terminals for the line circuits,and intermediate connecting circuits with term nals adapted to operateinterchangeably with each connecting said switching terminals, 1 circuitincluding a detector whereby the oscillator current is rectified andtransmitted' over the subscribers line as" a high unmodulated highpotential pulsating current, adapted to combine with received radiocarrier waves to produce an asymmetric modulated beat wave.

4. In asystem of broadcast distribution, a central station, asubscribers station, and a line circuit interconnecting them, a broadeast waveabsorbing device at the subscribers station, a receiving anddemodulating apparatus for broadcast waves comprising a vacuum tubedetector located'at the central station with'its plate circuit extended:over munication betweenv thefcentral station and the subscribers'station by the utilization of,

. the energy of. said plate. circuit.

station, a plurahtyof subscribers stations and them,

switchingmeans for coupling said-oscillator line circuit throughssaidinterers stations,and wired line circuits interconmeeting them, tion forreceiving broadcast waves and for i the subscribers line, as a highfrequenc 'modulated'; high potential pulsating current for use in.demodulating received. ra- 1 "die broadcast :waves, andemeanstransmitting them to the line cillator circuit at'the central.

to supply waves for combination withftherev ceived radio broadcastwaves,

intermediate connecting so .tral station each 5. phone system comprisinga telephone central wired line circuits"interconnecting-them, a

b1 11 frequency Wave receiving device at each cribers station,

station, means toof said tube over central station to. the connectedsubscriber-3s station over the plate circuit of said vacuum I 'tube. i Qv 6. In a system of radio broadcast distribu-.

tion, a central station,

and asubscribers station and a w red line c rcu t interconnectinganoscillator circuit. at the central station,;in intermediate connectingcircuit and circuit to the circuit including a lator current isrectified and transmitted over irect lishing telephonic communicationbetween tion over the high potential direct current circuit circuits, anosa plurality of circuits cally conducting vacuum tube, and. switchingmeans for connecting the oscillatorin common' to a plurality ofsubscribers flines;

A combined radio broadcast and tele vacuum tube detector responsive ademodulating circuit having its plate circuit connected to said re forsaidhighffrequency waves comprising a,

vacuum tubeat the central. complete the plate circuit any one of saidline circuits,

and means for 'es- ,tablishing telephone communicationJfrom-the ingdevice at said station,

mediate connecting. OlICllit, said connecting. detector wherebytheoscilfor estabthe central station and the subscribers' staiand causingthe at the cen-' comprising an asymmetry through' individual connectingcircuits, soas 8. Ina system ofbroadca'st distribution, a"

receiving station, a broadcast wave absorbing device at said station,and a receiving and emodulating apparatus for broadcast waves comprisinga source of oscillations and a thereto and centrahzed distributionsystem is-maintained.

*9. In a system of broadcast distribution, a receiving station, abroadcast wave absorband a receiving and demodulating apparatusforbroadcast waves comprising means for supplying said station withunmodulated high potential pulsating.

direct current at a'frequency of the same order as that of the;broadcast waves and means at said station for combining said currentsbroadcast waves to; produce audible eflects in e0v j v ca I produceaudible waves in a su1t-' i with the. absorbed energy of said modulateda telephone receiver, sald receiving anddemodulating apparatus beingseparated, whereby a centralized distribution systemis' maintained. I

10. In a system of broadcast distribution the method of receivingsignals modulated I i I a on carrier waves of superaudio frequency 7. Ina system of'radio broadcast distribus tion,'a central station, apluralityofsubscribwhich consistsfin absorbing the energy ofsa'id;waves, producingata distant pointother en-" ulsating-current atafrequency of the same waves, transmitenergy,

orgy in the form of unmodulated asymmetric means at each'subscriberssta- I Iorder as that of the absorbed ting said produced station adaptedcombining said produced energy, with said absorbed waves:

nalsignal modulations.

signature.

resultant current waveto prod duce sound waves correspondingto theorigia r a In testimony whereof' I hereuntolaflixmy 1 Y

